As a side note, the closed questions are not deleted from the web site because Stack Exchange takes a conservative approach when it comes to deletion. Nevertheless some questions do get deleted. The Help Center[1] and Meta[2] have more details on this.
> Questions that are extremely off topic, or of very low quality, may be removed at the discretion of the community and moderators.
In my experience, this is completely false, it should be reworded as "Questions that moderators like to remove on a whim".
The fact that a moderator (or group of moderators) don't find a question valuable doesn't mean that it is not valuable for the rest of the world, and this applies specifically with questions about recommendations.
[1]: http://stackoverflow.com/help/deleted-questions
[2]: http://meta.stackexchange.com/q/5221/135744